U.S. Pat. No. 3,745,360 describes a radiation detector that, like the present invention, has a circle-shaped outer contour. However, the reference differs from the present invention in that: 1) four radiation-sensitive resistances are arranged in a bridge circuit, rather than a single continuous photoconductor being used; 2) the radiation-sensitive resistances do not have a dual interleaved spiral configuration; 3) the reference is a staring type of detector, rather than one which is circularly scanned; and 4) it would be hard to use this technique with the preferred HgCdTe of the present invention because HgCdTe has too low a resistance.
U.S. Pat. No. 3,995,159 discloses a rectangular HgCdTe photoconductive element that is designed to be part of a larger array. It does not have a dual spiral pattern. It is used with a linear raster scan, rather than with a circular scan.
U.S. Pat. No. 4,024,397 is an infrared thermistor bolometer detector that senses temperature differentials by means of changes in resistance. Current and voltage differentials are measured, as in the present invention. However, the one or two bolometer flakes 28, 29 are not configured in a dual spiral pattern.
U.S. Pat. No. 4,027,160 discloses an array of detectors of rectangular size, using various reticle patterns, including zig zag ones. It does not disclose a detector having a dual spiral pattern.
U.S. Pat. No. 2,999,177 discloses a lead sulfide vidicom, i.e., a mosaic array of many rectangular monolithic lead sulfide detectors. Information is stored in the array, then interrogated by an electron beam.
U.S. Pat. No. 3,426,198 discloses an array of square monolithic lead sulfide detectors.
U.S. Pat. No. 3,727,057 discloses an array of rectangular photoconductive detectors having oppositely poled adjacent elements.